His talks with President George W Bush have been brought forward by 24 hours to Sunday.

Mr Bush demanded that Mr Arafat "act swiftly and decisively" against the organisations that support those who carried out the attacks.

US Defence Secretary Donald Rumsfeld, meanwhile, said the balance had changed in the region as a result of the attacks.

"The only way to defend against terrorists is to go after the terrorists," he said, appearing to back Israel's controversial policy of targeted assassinations of individuals who threaten its citizens.

Country shaken

Saturday night's blasts went off in quick succession in a busy Jerusalem neighbourhood packed with restaurants and cafes, shortly after midnight local time.

Twenty minutes later, a car bomb explosion in a nearby side street sent screaming survivors running in all directions.

Nail bombs are designed to create maximum carnage

The area was particularly busy, following the end of the Jewish Sabbath.

A witness, Eli Shetreet, told the Associated Press news agency he had seen bodies hurled in
the air by the blasts.

"People were crying, falling, and there
was the smell of burning hair," said Shetreet, 19.

Blood was splattered
across shop windows, with pieces of flesh and metal strewn on the ground.

Blame and denial

An Israeli Government official said Mr Arafat was guilty of a "total lack of action in the domain of fighting terror".

But the Palestinian leadership issued a strongly-worded statement, condemning the attacks and pledging to track down those responsible.

The car bomb exploded as 20 people were trying to move the vehicle away

The militant group Hamas, on its website, claimed responsibility for the Jerusalem and Haifa attacks.

Hours after the Jerusalem blasts, Israeli forces arrested several alleged militants in the village of Abu Dis on the outskirts of the city.

Palestinian police arrested a top member of Islamic Jihad, Mohammed al-Hindi after a gun battle at his Gaza home on Saturday.

Hamas and fellow militants Islamic Jihad have threatened to avenge Israel's killings of prominent members of militant groups.

Condemnation and messages of sympathy came from around the world, with Jordan also urging Israel to show restraint in the interests of peace.

Egypt strongly condemned the attacks, as did France, Russia and many other countries.

US demand

Mr Zinni was reportedly heckled by angry Israeli mourners

Senior US envoy Anthony Zinni - visiting Israel and Palestinian-controlled areas to try to secure a ceasefire - is reported to have been heckled by angry Israelis as he laid a wreath to the victims of the bombings.